code: def _handle_missing_trial_types(events):
      """Create 'dummy' events trial_type if the column is not present."""
      if "trial_type" not in events.columns:
          warnings.warn(
              "'trial_type' column not found in the given events data."
          )
          events["trial_type"] = "dummy"
      return events
  
file_path: nilearn/nilearn/glm/first_level/experimental_paradigm.py
imports: import warnings
  import pandas
  from pandas.api.types import is_numeric_dtype
label_desc: Use image node_id 3 for calling a global function with example usage: _handle_missing_trial_types(events) and returns: events